Watch wildfire smoke blanket most of the country in this time lapse of satellite data

It has been an exceptionally smoky summer in the United States, as wildfires burning in the western United States and Canada have sent plumes of smoke over much of the continent.

For a sense of just how smoky it is, consider these two satellite-derived images of smoke cover, produced by the National Oceanic and Atmospheric Administration (NOAA). First, here’s the fire and smoke situation across North America as of March 21 this year. The red dots are the locations of wildfires, while the grayish splotches show the smoke they produce.

NOAA generates new images daily, so I’ve compiled the past 100 or so into a GIF going back to the beginning of May. It shows the ebb and flow of atmosphere smoke as North American wildfires ignite and die out. You can see the amount of smoke increase dramatically in the past few weeks.

The agency cautions that there’s room for error in its measurements. Its analysts' “ability to detect fires and smoke can be compromised by many factors, including cloud cover, tree canopy, terrain, the size of the fire or smoke plume, the time of the day, etc.”

Research has shown that even low levels of outdoor air pollution can cause notable deficits in cognitive performance and worker productivity. A 2014 study found that small particle pollution concentrations of just 20 micrograms per cubic meter — well below Environmental Protection Agency guidelines for 24-hour exposure — caused significant drops in the productivity of indoor agricultural workers, resulting in reduced pay for the workers affected.

Atmospheric smoke can cause air pollutant levels to surge well beyond those numbers. In parts of Idaho, for instance, current small particle pollutant concentrations are coming in at more than 100 micrograms per cubic meter.